"use client";

/**
 * Client-side file intake for an assignment: validates photos and documents,
 * reads documents in the browser (lib/documents) and compresses photos
 * (lib/image). The raw files never leave the device — everything reaches the
 * server as text and JPEG data URLs.
 *
 * The same building blocks the /create screen uses, packaged for the homework
 * screen (which has its own caps and wording).
 */

import { useCallback, useRef, useState } from "react";

import {
  describeDocumentError,
  documentKindOf,
  extractDocument,
  isDocumentFile,
  type DocumentKind,
  type ExtractedDocument,
} from "./documents";
import { MAX_IMAGES, describeFileError, isImageFile, prepareImage, type PreparedImage } from "./image";
import { t } from "./i18n";
import { uid } from "./utils";

export type IntakeDocument = {
  id: string;
  name: string;
  kind: DocumentKind;
  status: "extracting" | "ready" | "error";
  progress?: string;
  extracted?: ExtractedDocument;
  error?: string;
};

export function useNotesIntake(options: {
  maxImages?: number;
  maxDocuments?: number;
  /** i18n key for “too many photos”, with an {n} placeholder. */
  tooManyPhotosKey: string;
  /** i18n key for “too many documents”, with an {n} placeholder. */
  tooManyDocsKey: string;
}) {
  const maxImages = options.maxImages ?? MAX_IMAGES;
  const maxDocuments = options.maxDocuments ?? 6;
  const tooManyPhotosKey = options.tooManyPhotosKey;
  const tooManyDocsKey = options.tooManyDocsKey;

  const [images, setImages] = useState<PreparedImage[]>([]);
  const [documents, setDocuments] = useState<IntakeDocument[]>([]);
  const [fileError, setFileError] = useState<string | null>(null);
  const [busy, setBusy] = useState(false);
  /** Mirrors of the current lists; React defers state updaters. */
  const imagesRef = useRef<PreparedImage[]>([]);
  const documentsRef = useRef<IntakeDocument[]>([]);

  const addFiles = useCallback(
    async (files: File[]) => {
      if (files.length === 0) return;
      setFileError(null);
      setBusy(true);

      const problems: string[] = [];
      const imageFiles: File[] = [];
      const documentFiles: File[] = [];

      for (const file of files) {
        if (isImageFile(file)) {
          const problem = describeFileError(file);
          if (problem) problems.push(problem);
          else imageFiles.push(file);
        } else if (isDocumentFile(file)) {
          const problem = describeDocumentError(file);
          if (problem) problems.push(problem);
          else documentFiles.push(file);
        } else {
          problems.push(t("upload.unsupported", { name: file.name }));
        }
      }

      const documentRoom = Math.max(0, maxDocuments - documentsRef.current.length);
      const acceptedDocuments = documentFiles.slice(0, documentRoom);
      if (documentFiles.length > documentRoom) problems.push(t(tooManyDocsKey, { n: maxDocuments }));

      // Documents are read asynchronously (pdf.js can take a while for scans).
      for (const file of acceptedDocuments) {
        const kind = documentKindOf(file);
        if (!kind) continue;
        const item: IntakeDocument = { id: uid("doc"), name: file.name, kind, status: "extracting" };
        documentsRef.current = [...documentsRef.current, item];
        setDocuments((current) => (current.some((entry) => entry.id === item.id) ? current : [...current, item]));

        const update = (patch: Partial<IntakeDocument>) =>
          setDocuments((current) =>
            current.map((entry) => (entry.id === item.id ? { ...entry, ...patch } : entry)),
          );

        try {
          const extracted = await extractDocument(file, (progress) => update({ progress: progress.message }));
          update({ status: "ready", extracted, progress: undefined });
        } catch (error) {
          update({
            status: "error",
            error: error instanceof Error ? error.message : t("upload.couldNotReadDoc"),
          });
        }
      }

      const photoRoom = Math.max(0, maxImages - imagesRef.current.length);
      const acceptedImages = imageFiles.slice(0, photoRoom);
      if (imageFiles.length > photoRoom) problems.push(t(tooManyPhotosKey, { n: maxImages }));

      const prepared: PreparedImage[] = [];
      for (const file of acceptedImages) {
        try {
          prepared.push(await prepareImage(file));
        } catch {
          problems.push(t("upload.couldNotReadFile", { name: file.name }));
        }
      }
      if (prepared.length > 0) {
        imagesRef.current = [...imagesRef.current, ...prepared];
        setImages((current) => [...current, ...prepared]);
      }

      if (problems.length) setFileError(problems.slice(0, 3).join(" "));
      setBusy(false);
    },
    [maxDocuments, maxImages, tooManyDocsKey, tooManyPhotosKey],
  );

  const removeImage = useCallback((id: string) => {
    imagesRef.current = imagesRef.current.filter((image) => image.id !== id);
    setImages((current) => current.filter((image) => image.id !== id));
  }, []);

  const removeDocument = useCallback((id: string) => {
    documentsRef.current = documentsRef.current.filter((entry) => entry.id !== id);
    setDocuments((current) => current.filter((entry) => entry.id !== id));
  }, []);

  const clear = useCallback(() => {
    imagesRef.current = [];
    documentsRef.current = [];
    setImages([]);
    setDocuments([]);
    setFileError(null);
  }, []);

  return { images, documents, fileError, busy, addFiles, removeImage, removeDocument, clear };
}